There are two types of semiconductor device manufacturing systems: a job shop system and a flow shop system. In a job shop system, plural semiconductor device manufacturing apparatuses of a kind are installed for each step to assure a high operation rate. In a flow shop system, a series of different steps are connected in a serial processing apparatus so that the different steps are serially performed. (As a compromise between both, a modular system is also available.)
Semiconductor device manufacturing techniques for job shop process systems are disclosed in Japanese Unexamined Patent Publication No.181184/1996 and No. 237095/1995.
Japanese Unexamined Patent Publication No.181184/1996 describes a technique for a job shop process system in which workpiece conveyance and processing are carried out between processing apparatuses under design cycle time control and workpieces are freely conveyed between processing apparatuses.
Japanese Unexamined Patent Publication No.237095/1995 describes a technique for a job shop process system in which there are plural working areas in each of which plural processing apparatuses of a kind are connected by a conveyor system, and workpieces are moved between processing apparatuses as if they were moved between several flow shops.
Among other related techniques is a technique disclosed by Japanese Unexamined Patent Publication No.145022/1999 which combines flow shop and job shop manufacturing lines to perform various steps efficiently. In this system, among a series of manufacturing steps, some steps suitable for a flow shop system are arranged according to a flow shop layout and the other steps are arranged according to a job shop layout.
Furthermore, Japanese Unexamined Patent Publication No.99111/2000 describes a production control technique which is related to priority-based lot management. In this technique, a comparison is made in absolute priority between products in process and incoming products to determine which products should be processed next.
However, the above-mentioned techniques do not include reference to means to optimize the selection of processing apparatuses for prioritized/non-prioritized products, optimize the selection of processing apparatuses for mass-produced products/small-lot products or differentiate process scheduling.
Besides, there is no reference to means to save labor required to rearrange the processing line for product type change or in case of a system failure, by using a loader unit effectively in a flow shop system (serial processing system).
An object of the present invention is to provide a semiconductor device manufacturing method which substantially shortens the processing time.
The above and other objects and novel features of the invention will be apparent from the following description taken in connection with the accompanying drawings.